By transformation of Saccharomyces cerevisiae cells harboring a disrupted gene for chitin synthetase 1 with a yeast DNA library, a strain was isolated that over-produces chitin synthetase 2 by a factor of 50. Studies are continuing to establish whether the plasmid contained in those cells bears the structural gene for chitin synthetase 2 and to determine the function of this enzyme in yeast. Chitin synthetase 1 was purified by a new procedure involving a hybrid protein with beta-galactosidase and antibodies against the enzyme have been elicited in rabbits. The solubilized GTP-binding factor from S. cerevisiae (1-3) beta- glucan synthetase had been partially purified.